A comparison of arrived dose to the heart in the treatment of breast cancer in different modes of proton radiation by proton therapy using Monte Carlo simulation

Introdution: Today, the Advantages of radiation therapy by charged particles is indicated for the treatment of cancerous. During the passing of proton beam in the body tissues, secondary particles produce, which penetrate to the body healthy tissues and cause damage. The aim of this research was calculating the Spread out Bragg Peak for covering the breast cancer and investigating arrived dose to the different parts of the heart during the treatment process. Methods: In this simulation study, a spherical tumor with a diameter of 1 cm considered in right breast tissue in MIRD phantom and then irradiated by proton of right and front sides of the body. Simulations are performed using the MCNPX code. Results: The Spread out Brag Peak calculated to cover the breast cancer in two cases of radiation. In the radiation of front and right, the deposited Dose due to The Proton Particle in tumor are 4.25 nGy and 4.12 nGy, respectively. The dose due to the protons and secondary particles in different parts of the heart calculated and compared for two modes of radiation. Energy Ranges of neutrons was about 55 MeV and for electrons and photons was less than 20 MeV. Although, the dose due to the secondary particles was very low in comparison of protons dose. Conclusion: In proton therapy, a large portion of the dose is evacuated in the tumor. Proton radiation of the front in comparison of the right leads to the more dose deposit in the tumor and heart.